2. Natural Bridge Caverns lies within the recharge zone of the Edwards Aquifer.
Figure from Musgrove (2000) after Burchett et al. (1986) and Brown et al. (1992); precipitation contours from Larkin and Bomar (1983).

3. Map from Elliott and Veni (1994)
This is the map view of Natural Bridge Caverns.
Elliott, W. R., and Veni, G., eds., 1994, The Caves and Karst of Texas NSS Convention Guidebook, National Speleological Society, Huntsville,
AL, 342 p.
Map from Elliott and Veni (1994)
The cave transports water to recharge the Edwards Aquifer.

4. Water can enter the cave through fractures (fracture flow) or by seeping through the permeable rock itself (diffuse flow).
Diffuse Flow
Fracture Flow

5. As the slightly acidic rain water passes through rock, it dissolves away calcite and enlarges cave passages.

6. Stalactite
Cave formations such as stalactites, stalagmites, columns, and flowstone develop when the calcite is redeposited.
Column
Stalagmite
Flowstone

8. The North Cavern has several spectacularly clear pools of water.
Calcite deposits around the rims of the pools indicate past water levels.

9. Map from Elliott and Veni (1994)
Purgatory Creek is a perfect location to observe changes in the water level of the aquifer.
After heavy rains, the water table can rise to flood this entire room, submerging the walkway.
Elliott, W. R., and Veni, G., eds., 1994, The Caves and Karst of Texas NSS Convention Guidebook, National Speleological Society, Huntsville,
AL, 342 p.

10. Science in Natural Bridge Caverns
University of Texas scientists have set up experiments to study the relationships between water chemistry, drip rates, and how fast formations grow.

11. Samples from glass plates like this one at Castle Tabletop give an exact measurement calcite deposition of over time.
Water samples collected from the drips above the formation are analyzed for chemical composition.

12. How you can help protect the cave?
Remember, the Natural Bridge Caverns are LIVING caves. Touching formations or getting off trail will cause irreparable damage.
Keep the caves as clean as possible. Do not bring food, candy, gum, drinks, water bottles, backpacks, or strollers into the cave.
Stay with the group and listen to the guide. Several tours are in the cave at the same time.

13. Enjoy your adventure to Natural Bridge Caverns!